Exercise 4 Page 387

Let's think about measuring and constructing the segment separately.

Constructing a Line Segment

We can construct a line segment using any straightedge and writing utensil. We just need to draw a straight line. Any straight line with a finite length is a line segment.

Measuring a Line Segment

Now, let's draw the line segment we would like to measure.

To measure this line segment, we need to define a unit length and we need to construct a second line segment with the same length as our unit length.

We then need to count how many times our second line segment fits into our first line segment.

In this case, our line segment was $4$ units long. Typically we would use a well-known unit of measure such as inches, meters, or yards.